This invention relates to an improved retaining wall construction and, more particularly, to a retaining wall construction comprised of modular blocks, in combination with tie-back and/or mechanically stabilized earth elements and compacted particulate or soil. This invention further relates to the stabilizing elements for mechanically stabilized earthen structures and the combination thereof with various facing elements.
In U.S. Pat. Nos. 3,686,873 and 3,421,326, Henri Vidal discloses a constructional work now often referred to as a mechanically stabilized earth or earthen structure. The referenced patents also disclose methods for construction of mechanically stabilized earth structures such as retaining walls, embankment walls, platforms, foundations, etc. In a typical mechanically stabilized earth construction, particulate earthen material interacts with longitudinal elements such as elongated steel strips positioned at appropriately spaced intervals in the earthen material. The elongate elements are generally arrayed for attachment to reinforced precast concrete wall panels and, the combination forms a cohesive embankment and wall construction. The longitudinal or elongate elements, which extend into the earthen work, interact with compacted soil particles principally by frictional interaction and thus mechanically stabilize the earthen work. They are often termed stabilizing elements. The elongate, longitudinal or stabilizing elements may also perform a tie-back or anchor function.
Various embodiments of the Vidal development have been commercially available under various trademarks including the trademarks, REINFORCED EARTH embankments and RETAINED EARTH embankments. Moreover, other constructional works of this general nature have been developed. By way of example and not by way of limitation, Hilfiker in U.S. Pat. No. 4,324,508 discloses a retaining wall comprised of elongated panel members with wire grid mats attached to the backside of the panel members projecting into an earthen mass.
Vidal, Hilfiker and others generally disclose large precast, reinforced concrete wall panel members cooperative with strips, mats, etc. to provide a mechanically stabilized earth construction. Vidal, Hilfiker and others also disclose or use various shapes of precast concrete wall panel members. It is also noted that in constructions disclosed by Vidal and Hilfiker, the elements interactive with the compacted earth or particulate behind the wall panels or blocks, are typically rigid steel strips or mats which rely upon friction and/or anchoring interaction with the particulate, although ultimately, all interaction between such elements and the earth or particulate is dependent upon friction. Wire mats or mesh are also disclosed as vertical facing elements in place of the concrete panel members.
In such circumstances, smaller precast blocks rather than large precast panels may be used to define the wall. Forsberg in U.S. Pat. No. 4,914,876 discloses the use of smaller retaining wall blocks in combination with flexible plastic netting as a mechanically stabilizing earth element to thereby provide a mechanically stabilized earth retaining wall construction. Using flexible plastic netting and smaller, specially constructed blocks arranged in rows superimposed one upon the other, reduces the necessity for large or heavy mechanical lifting equipment during the construction phase of such a wall.
Others have also suggested the utilization of facing blocks of various configurations with concrete anchoring and/or frictional netting material to build an embankment and wall. Among the various products of this type commercially available is a product offered by Rockwood Retaining Walls, Inc. of Rochester, Minn. and a product offered by Westblock Products, Inc. and sold under the trade name, Gravity Stone. Common features of these systems appear to be the utilization of various facing elements in combination with backfill, wherein the backfill is interactive with plastic or fabric reinforcing and/or anchoring means which are attached to the facing elements. Thus, there is a great diversity of such combinations available in the marketplace or disclosed in various patents and other references.
Nonetheless, there has remained the need to provide an improved system utilizing anchoring and/or frictional interaction of backfill and elements positioned in the backfill wherein the elements are cooperative with and attachable to facing elements, including blocks which are smaller and lighter than large facing panels such as utilized in many installations or with wire mesh facing elements. The present invention comprises an improved combination of elements of this general nature and provides enhanced versatility in the erection of retaining walls and embankments, as well as in the maintenance and cost of such structures. The present invention further comprises various stabilizing elements useful in the construction of such civil engineering structures.
Briefly, the present invention comprises a combination of components to provide an improved civil engineering structure including a retaining wall system or construction. The invention also comprises the components or elements from which the civil engineering structure is fabricated. A feature of the invention is a modular wall block which may be used as a facing component for a retaining wall construction. The modular wall block may be unreinforced and dry cast. The block includes a front face which is generally planar, but may be configured in almost any desired finish and shape. The wall block also includes generally converging side walls, generally parallel top and bottom surfaces, a back wall, vertical throughbores or passages through the block specially positioned to enhance the modular character of the block, and counterbores, associated with the throughbores, having a particular shape and configuration which permit the block to be integrated with and cooperative with various types of anchoring and/or earth stabilizing elements. Special corner block and cap block constructions are also disclosed.
Various earth stabilizing and/or anchor elements are also disclosed for cooperation with the modular wall or face block and other blocks or facing elements. An embodiment of the earth stabilizing and/or anchoring elements includes first and second generally parallel tensile rods which are designed to extend longitudinally from the modular wall block into compacted soil or an earthen work. The ends of the tensile rods are configured to fit within the counterbores defined in the top or bottom surface of the modular wall or facing block. Angled or transverse cross members connect the parallel tensile rods and are arrayed not only to enhance the anchoring characteristics, but also the frictional characteristics of interaction of the tensile rods with earth or particulate material comprising the civil engineering structure. Numerous alternative stabilizing elements are disclosed as well as various systems and components for attachment of the stabilizing elements to facing elements such as wall blocks, panels, and the like.
An alternative stabilizing element cooperative with the modular blocks comprises a harness which includes generally parallel tension arms that fit into the counterbores in the blocks and which cooperate with the vertical anchoring rods so as to attach the tension arms to the blocks. The harness includes a cross member connecting the opposite tension arms adjacent the back face outside of the modular block. The cross member of the harness may be cooperative with a geotextile strip, for example, which extends into the earthen work behind the modular wall block. Again, the harness cooperates with vertical anchoring rods which extend into the passages or throughbores defined in the modular blocks.
The described wall construction further includes generally vertical anchoring rods that interact both with the stabilizing elements and also with the described modular blocks by extending vertically through the throughbores in those blocks while simultaneously engaging the stabilizing elements. Various other alternative permutations, combinations and constructions of the described components are set forth.
Thus it is an object of the invention to provide an improved retaining wall construction comprised of modular blocks and cooperative stabilizing elements that project into an earthen work or particulate material.
It is a further object of the invention to provide an improved and unique modular block construction for utilization in the construction of a improved retaining wall construction.
Yet another object of the invention is to provide a modular block construction which may be easily fabricated utilizing known casting or molding techniques.
Yet a further object of the invention is to provide a substantially universal modular wall block which is useful in combination with earth retaining or stabilizing elements as well as anchoring elements.
Yet another object of the invention is to provide numerous unique earth anchoring and/or stabilizing elements that are cooperative with a modular wall or facing block or other facing elements.
Another object of the invention is to provide various stabilizing element designs and also various useful designs for components to attach stabilizing elements to facing elements.
Yet a further object of the invention is to provide a combination of components for manufacture of a retaining wall system or construction which is inexpensive, efficient, easy to use and which may be used in designs susceptible to conventional design or engineering techniques.
Another object of the invention is to provide a design for a modular block which may be used in a mechanically stabilized earth construction or an anchor wall construction wherein the block may be unreinforced and/or manufactured by dry cast or pre-cast methods, and/or interactive with rigid, metal stabilizing elements as well as flexible stabilizing elements such as geotextiles.
These and other objects, advantages and features of the invention will be set forth in the detailed description which follows.